The most effective ways to help students retain information all share one principle: they force the brain to actively reconstruct knowledge rather than passively receive it. Techniques like retrieval practice, spaced review, and interleaving have decades of research behind them, and they work across age groups and subjects. Here’s what the evidence says and how to put each strategy into practice.
Why Students Forget So Quickly
Memory decay is steep and fast. In a replication of the classic forgetting curve research, a subject retained only about 32% of learned material after one day, 23% after two days, and just 17% after six days with no review. That’s not a sign of poor studying. It’s how human memory works by default. The brain discards information it doesn’t actively use.
This means that a single exposure to material, no matter how clear the lecture or how good the textbook, is almost never enough. Retention requires repeated, well-timed engagement with the content. The strategies below are designed to interrupt that forgetting curve at the points where it drops fastest.
Retrieval Practice Over Rereading
Asking students to pull information from memory is significantly more effective than having them reread notes or textbook passages. This is called retrieval practice, and it works because the act of remembering strengthens the neural pathways that store that information. Rereading feels productive because the material seems familiar, but familiarity is not the same as knowing.
In practice, retrieval looks like low-stakes quizzes at the start of class, flashcard drills, or asking students to write down everything they remember about yesterday’s lesson before opening their notes. The key is that students must generate answers from memory, not recognize them from a list. One important nuance from research published in NPJ Science of Learning: retrieval practice benefits students with higher working memory capacity more than those with lower capacity. That means some students may need additional scaffolding, like partial prompts or cued recall, before they can benefit fully from open-ended retrieval tasks.
Space Out Review Sessions
Cramming works for tomorrow’s test. It fails for anything beyond that. Spaced repetition, where you revisit material at gradually increasing intervals, dramatically improves long-term retention. For material students need to remember six months later, research from the National Library of Medicine found that a review interval of seven days between sessions outperformed a three-day interval.
A practical spacing schedule might look like this: review new material the day after it’s introduced, again three to four days later, then a week after that, then two weeks, then a month. Each review session can be brief. What matters is the gap between sessions, which forces the brain to rebuild its access to the memory each time.
Spaced repetition software like Anki or Quizlet automates these intervals using algorithms that track what each student knows and schedules reviews accordingly. A case study introducing this software in a university Arabic course found that students rated it more motivating than traditional study methods, which matters because consistency is the biggest challenge. The software only works if students actually use it regularly. If you assign it, build in accountability structures like brief in-class checks on usage or linking it to participation credit.
Mix Topics Within a Single Session
Most curricula are organized in blocks: spend a week on fractions, then a week on decimals, then a week on percentages. Interleaving flips this by mixing problem types within a single study session. Instead of ten fraction problems followed by ten decimal problems, students alternate between them.
Interleaving feels harder in the moment, and students often perform worse during practice. But on delayed tests, interleaved practice consistently outperforms blocked practice. Research in Behavioral Sciences found that when students were memorizing material, interleaving was significantly more effective than blocking (74% vs. 60% accuracy). However, the relationship reversed when students were trying to discover underlying rules or patterns, where blocking led to better outcomes (53% vs. 29%).
The takeaway for educators: use interleaving when students are building fluency with material they’ve already been taught. Use blocked practice when they’re first learning a new concept and need to identify its structure. The transition from blocked to interleaved practice can happen within the same unit, moving from focused introduction to mixed review.
Ask “Why” and “How” Questions
Elaborative interrogation is a simple technique where students are asked to explain why a fact is true or how a process works, rather than simply being told. Instead of presenting “the heart has four chambers,” you ask: “Why would the heart need four chambers instead of two?” This forces students to connect new information to things they already know, building a web of associations that makes the new fact easier to retrieve later.
These prompts work because they push students to make explanatory inferences, actively reasoning about the material rather than recording it. You can embed elaborative interrogation into lectures by pausing after a key point and asking the class to explain it to a neighbor. You can also build it into homework by replacing “define X” questions with “explain why X happens” questions. The quality of the explanation matters less than the act of generating one.
Pair Words With Visuals
The brain processes verbal information and visual information through separate channels. When both channels encode the same concept, the result is a richer, more interconnected memory trace. This is dual coding, and it’s one of the most practical strategies available to teachers.
Dual coding happens when you draw a diagram on the whiteboard while explaining a process, display an image alongside a key term, or ask students to sketch a concept after hearing about it. The critical piece is that the visual and verbal elements should represent the same idea simultaneously. A chart of the water cycle shown during a lecture on evaporation creates referential connections between what students see and what they hear. The more of these cross-channel connections the brain forms, the more retrieval paths exist when it’s time to remember.
Students can use this on their own, too. Encourage them to turn their text-heavy notes into concept maps, timelines, or simple sketches. The drawings don’t need to be artistic. A stick-figure diagram of cellular division, drawn from memory, engages both the visual and verbal systems and doubles as retrieval practice.
Teach Students to Judge Their Own Learning
One of the biggest barriers to retention is that students are poor judges of what they actually know. Research in CBE Life Sciences Education found that students often rate their confidence based on whether material looks familiar rather than whether they can actually recall and use it. This means a student can reread their notes, feel confident, and then bomb the exam.
The fix is metacognitive monitoring: teaching students to evaluate their knowledge based on retrieval, not recognition. The most direct method is self-testing. If a student can answer a practice question correctly from memory, they likely know the material. If they can’t, that feedback tells them exactly where to focus. This creates a loop: study, test yourself, identify gaps, study the gaps, test again.
Instructors can build this into class by giving practice exams with answer keys and asking students to categorize each topic as “solid,” “shaky,” or “lost.” This simple exercise redirects study time toward the material that actually needs it, rather than the material that feels most comfortable to review. Even during high-stakes exams, students who monitor their confidence question by question and return to low-confidence answers tend to make more productive answer changes.
Sleep Protects New Memories
Sleep is not downtime for the brain. During deep sleep, the brain replays and consolidates new memories, transferring them from short-term to long-term storage. Research in Brain Sciences found that students who slept after learning new material improved their recall, while those who stayed awake over the same time period showed a decline. The proportion of time spent in full sleep cycles correlated strongly with how much students benefited, accounting for 56% of the variance in memory improvement.
For educators, the practical implications are limited but real. Assigning new or difficult material earlier in the day gives students time to review it before sleep. Discouraging all-night study sessions matters not just for wellbeing but for actual learning outcomes. And when students report poor sleep, it helps to know that their retention is genuinely compromised, not that they didn’t try hard enough.
The Note-Taking Question
A widely cited 2014 study suggested that handwriting notes led to better conceptual understanding than typing. More recent research complicates that picture. A study of medical students published in the Journal of Educational Evaluation for Health Professions found no significant difference in either factual recall or conceptual understanding between tablet, laptop, and handwritten notes.
The method of note-taking matters less than what students do with their notes afterward. Notes that are reviewed through retrieval practice and spaced repetition will outperform notes that are perfectly organized but never revisited, regardless of whether they were typed or handwritten. If you have a preference for your classroom, enforce it, but don’t expect the medium alone to move the needle on retention. The real leverage is in what happens after the notes are taken.